1. Field of the Invention
The present invention relates to a sound processing apparatus, a sound processing method, and a sound processing program, and more particularly to a sound processing apparatus, a sound processing method, and a sound processing program that can suppress howling with high accuracy.
2. Description of the Related Art
When sound collected by a microphone is amplified by an amplifier and then output from a public-address system such as a speaker, the output sound propagates through the air and is fed back to the microphone to form a closed loop. Depending on the condition such as volume or the position of each component, the amplitude of a specific frequency of an audio signal increases gradually, causing oscillation called howling.
A method of automatically suppressing howling is to detect the frequency (referred to below as the howling frequency) at which howling occurs by frequency analysis and reduce the gain of the howling frequency by creating a plurality of notch filters corresponding to the howling frequency (see, for example, Japanese Unexamined Patent Application Publication No. 2009-49921).